This is an adapter for the Rasbery camera v2 for a Leica microscope sidetube (Serie M400/500), The holes in the sidetube part is for M4 screews and all the holes in the camera holder part is for M2 screws. The adpater is for the HDMI kit from (https://www.tindie.com/products/freto/pi-camera-hdmi-cable-extension/).